Fuse mounting device



April 20, 1965 A. SOMMERS FUSE MOUNTING DEVICE Filed NOV. 14, 1961 INVENTOR. ALEX/S SOMMERS g r m Attorneys United States Patent FUSE MOUNTING DEVICE Alexis Summers, Warren, Pa., assignor to El-Tronics, Inc., Warren, Pa., a corporation of Pennsylvania Filed Nov. 14, 1961, Ser. No. 152,323 3 Claims. (Cl. 200-119) This inventionrelates to mountings for fuses having mounting terminals of the blade type and more particularly to adapters for mounting high-rupture capacity piercedblade fuses in existing fuse holders or mounts.

The National Electrical Manufacturers Association has adopted standards to which fuses of high rupture capacity are now manufactured. These fuses are designated by the industry as J type fuses. They are designed to have an interrupting capacity of 200,000 amperes.

Because of the physical dimensions which have been chosen by the industry for J type fuses, they are not interchangeable with fuses of other types. The blades of the J type fuse have slots or holes which enable the user to bolt the fuse to special clips which are standard equipment in fuse boxes now being made to take the J type fuse. The clamping pressure. of the clip bolt gives better assurance of good electrical connection at the interfaces between the fuse blade and clip than does the conventional clip which relies on spring pressure alone. The clip bolts are loosened to change the fuse.

The non-interchangeability between J type fuses and earlier types of fuses is desirable in order to discourage maintenance personnel from inadvertently substituting standard fuses of relatively low interruption capacity (say 15,000 amperes) in circuits which are capable of delivering much higher amperages on short circuit and which are therefore originally provided with J type fuses. The use of a fuse of too low a rating is hazardous because of the likelihood that operation of the fuse will be accompanied by explosion and fire.

The provision of J type fuses tend to obsolete many existing fuse holders or mounts which are designed to accept standard-size fuses but which are in use in applications calling for high rupture capacity of the fuse.

To meet this problem, the present invention provides a device for mounting ahigh-rupture-capacity pierced-blade fuse between a pair of fuse clips which the fuse blades cannot directly engage because the fuse is of the J type and is therefore too short, the device being adapted to discourage the subsequent substitution of a longer fuse in the same circuit, all this being done in such a way as to provide clamping engagement'between all current-transmitting interfaces (in the same manner that the above mentioned original-equipment special clips for J type fuses provide such clam-ping engagement) so that the adaptation effected by the invention is consistent with proper electrical performance of the connections under both operating and fault conditions.

The present invention makes it possible for users of I type fuses to adapt existing fuse holders or mounts to the special dimensions of J type fuses while guarding against use of such existing fuse holders or mounts with the sizes of fuses for which they were originally intended. Thus the use of the invention maintains the non-interchangeability safety feature originally contemplated for J type fuses, and at the same time avoids obsoleting oversized existing fuse holders or mounts.

By way of example, a description of one specific embodiment of the device is set forth below and in the ac.- companying drawings.

In the drawings, FIGURE 1 is an isometric view of a device connecting one end of a fuse to a fuse clip in the manner contemplated by the invention.

FIGURE 2 is an isometric'view of the adapter shown in FIGURE 1.

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FIGURE 3 is an isometric view of the clamp shown in FIGURE 1.

FIGURE 4 is an isometric view on a reduced scale illustrating a I type fuse positioned between two conventional mounting clips. f

In the illustrated apparatus, a high-rupture-capacity pierced-blade fuse 10 is to be mounted between a pair of two-leaved clips 11 and 12 (FIGURE 4) which the blades 13 and 14 of the fuse 10 cannot engage because the fuse is too short. The fuse 10 is the type of fuse designated in the industry as a J type and the blades 13 and 14 are pierced, that is, they are provided with holes or slots, such as the holes 15 illustrated in FIGURE 4.

As illustrated in FIGURE 2, there is provided a silverplated copper adapter 16 having an adapter plate 17 at one end. The adapter plate has two outside faces, only one of which can be seen in the drawings and is designated by the reference numeral 18. These two outside faces are spaced apart a given distance equal to the thickness of the edge 17' to thereby define an adapter blade plate suitable for reception in the fuse clip 11. The other end of the adapter 16 comprises a pair of adapter plate elements 19 and 20. Each member of this pair has an inside face. Only one of the inside faces is visible in FIGURE 2 and is designated by the reference numeral 21.

The inside faces of the adapter plate elements 19 and 20 are spaced apart a distance which is the same as the given distance between the outer face 18 and the other outer face of the adapter plate 17. The inside faces of the adapter plate elements 19 and 20 thereby define an adapter plate spacing suitable for reception of the pierced blade 13.

A removable clamping bolt 25 extends between the adapter plate elements 19 and 20 and is threadedly engaged with the adapter plate element 19 for drawing the adapter plate elements together to thereby releasably clamp them on the fuse blade 13. The bolt 25 extends through the hole 15 formed in the fuse blade 13 when the fuse is mounted on the adapter 16.

Means is provided to clamp the blade 17 of the adapter 16 within the fuse clip 11. A pair of clamping plates 31 and 32 surrounds the fuse clip 11. The clamps 31 and 32 are joined by a pair of high tensile steel socket head screws 33 and 34 which have peenable heads. The screw 33 extends between a first pair of corners of the clamping plates 31 and 32, being rotatably received in a lug formed in the clamping plate 32 and threadedly received in a corresponding lug formed in the clamping plate 31, the lugs being clearly illustrated in FIGURE 4.

The screw 34 extends between a second pair of corners of the clamping plates '31 and 32. The location of the second pair of corners is diametrically opposed to the location of the first pair of corners so that the plates 31 and 32 and all the elements between them are properly clamped together while at the same time proper clearance istprovided for the upstanding elements of the fuse clip 11 and the longitudinally extending blade 17 of the adapter is. The screw 34 is rotatably received in a lug formed in the clamping plate 32 and is threadedly received in a corresponding lug (not seen) formed in the clamping plate 31.

The material of which the clamps 31 and 32 are made is cast bronze to give the required rigidity and yet be non-magnetic. These clamps can be either of bronze, brass, or similar non-ferrous alloy either cast, or stamped from heavy gauge metal.

The assembled condition of the several elements is illustrated in FIGURE 1. It is to be noted that the interfaces between the elements of the mounting clip 11 and the blade 17 of the adapter 16 are subjected to the positive clamping pressure of the clamping plates 31 and '32 and the interfaces between the fuse blade 13 and the clamping p1ates19 and 2d of the adapter ldare subjected to the clamping pressure of the central bolt 25. Accordingly, the assembly provides clamping engagement between all current-transmitting interfaces in the same manner that original-equipment special clips for i type fuses provide for such clamping engagement, so that the adaptation effected by the invention is consistent with proper electrical performance of the connections under both operating and fault conditions,

When the assembly is completed, as shown in FIG- URE l, the heads of the socket head screws 33 and 34 are peened inwardly to prevent disturbance. The maintenance electrician is thereby discouraged from attempts to remove the clamp and substitute normal size fuses that are not of the I type and are not of proper rating.

in most applications it is desirable to duplicate the above-discussed apparatus at both ends of the fuse. This would be appropriate in the case illustrated in FIGURE 4 and the apparatus as above described would be duplicated. for association with the end between the fuse clip 12 and the fuse blade 1.4.

If it becomes necessary to replace thev fuse 18, the bolt 25 and the corresponding bolt at the opposite end of the fuse are loosened and removed from the slots 15. The fuse is then replaced and the bolts are reinserted and retightened.

in applications where it is advantageous to improve the connection between a fuse blade and a fuse clip and the fuse is of the proper length to be received in the clip, the clamps 31 and 32 may be used without the adapter 16. The clamping pressure increases the contact area at the interfaces between the blade'and clip and thus eliminates the premature fuse blowing caused by high resistances at the interfaces. Inadequate area of contact at the blade-clip interface appears to be a major factor in the overheating and failure of fuses.

The above description is given by way of example and not by way of limitation. The scope of the invention is defined in the following claims.

What is claimed is:

1. A device mounting a high-rupture-capacity piercedblade fuse between a pair of two-leaved fuse clips which the fuse blades cannot engage because the fuse is too short, and for discouraging the subsequent substitution of a longer fuse in the same circuit, said device comprising at least one adapter having an adapter blade at one end, said adapter blade being received in one of said fuse clips and having two outside faces spaced apart a given distance to define an adapter blade thickness suitable for such reception of said adapter blade, said adapter having at the other end a pair of adapter plate elements, each member of said pair of elements having an inside face, said inside faces receiving one of said fuse blades and being spaced apart said given distance to define an adapter plate spacing suitable for such reception of said one of said fuse blades, a removable clamping bolt extending through said one of said fuse blades and between said adapter plate elements for drawing said adapter plate elements together to releasably clamp said one of said fuse blades, and means clamping said adapter blade within said one of said fuse clips, said clamping means comprising a air of clamping plates having two flat inside faces positionable in face-to-face spaced apposition with said two outside faces of said adapter blade for fiat faceto-face clamping contact of each face of each of the two leaves of the associated fuse clip, said clamping means including socket head screws having peenable heads, said screws extending between said plates for nonreleasably tightening said plates against said one fuse clip and thereby clamping said adapter blade within said one fuse clip, said screws comprising a first screw extending between a first pair of corners of said clamping plates and a second screw extending between a second pair of corners of said clamping plate, the location of said second pair of corners being diametrically opposed to the location of said first pair of corners.

2. A device as defined in claim 1, in which said apparatus is duplicated for association with and between tl e remaining one of said pair of fuse clips and the remaining one of said fuse blades.

3. A device mounting a pierced-blade fuse between a pair of two-leavcd fuse clips which the fuse blades cannot engage because the fuse is too short, said device comprising at least one adapter having an adapter blade at one end, said adapter blade being received in one of said fuse clips and having two outside faces spaced apart a given distance to define an adapter blade thickness suitable for such reception of said adapter blade, said adapter having at the other end a pair of adapter plate elements, each member of said pair of elements having an inside face, said inside faces receiving one of said fuse blades and being spaced apart said given distance to define an adapter plate spacing suitable for such reception of said one of said fuse blades, a removable clamping bolt extending through said one of said fuse blades and between said adapter plate elements for drawing said adapter plate elements together to releasably clamp said one of said fuse blades, and means clamping said adapter blade between the sides of said one of said fuse clips, said clamping means comprising a pair of clamping plates having two fiat inside faces positionable in face-toface spaced apposition with said two outside faces of said adapter blade for fiat face-to-face clamping contact of each face of each of the two leaves of the associated fuse clip.

References Qited by the Examiner UNITED STATES PATENTS 1,953,343 4/34 Frank 200133 2,147,316 2/39 Ramsey 200l33 2,220,698 11/40 Adam et a1. 20013l OTHER REFERENCES German application 1,103,424, Mar. 30, 1961, K1. 21C 21/01.

BERNARD A. GILHEANY, Primary Examiner. 

3. A DEVICE MOUNTING A PIERCED-BLADE FUSE BETWEEN A PAIR OF TWO-LEAVED FUSE CLIPS WHICH THE FUSE BLADES CANNOT ENGAGE BECAUSE THE FUSE IS TOO SHORT, SAID DEVICE COMPRISING AT LEAST ONE ADAPTER HAVING AN ADAPTER BLADE AT ONE END, SAID ADAPTER BLADE BEING RECEIVED IN ONE OF SAID FUSE CLIPS AND HAVING TWO OUTSIDE FACES SPACED APART A GIVEN DISTANCE TO DEFINE AN ADAPTER BLADE THICKNESS SUITABLE FOR SUCH RECEPTION OF SAID ADAPTER BLADE, SAID ADAPTER HAVING AT THE OTHER END A PAIR OF ADAPTER PLATE ELEMENTS, EACH MEMBER OF SAID PAIR OF ELEMENTS HAVING AN INSIDE FACE, SAID INSIDE FACES RECEIVING ONE OF SAID FUSE BLADES AND BEING SPACED APART SAID GIVEN DISTANCE TO DEFINE AN ADAPTER PLATE SPACING SUITABLE FOR SUCH RECEPTION OF SAID ONE OF SAID FUSE BLADES, A REMOVABLE CLAMPING BOLT EXTENDING THROUGH SAID ONE OF SAID FUSE BLADES AND BETWEEN SAID ADAPTER PLATE ELEMENTS FOR DRAWING SAID ADAPTER PLATE ELEMENTS TOGETHER TO RELEASABLY CLAMP SAID ONE OF SAID FUSE BLADES, AND MEANS CLAMPING SAID ADAPTER BLADE BETWEEN THE SIDES OF SAID ONE OF SAID FUSE CLIPS, SAID CLAMPING MEANS COMPRISING A PAIR OF CLAMPING PLATES HAVING TWO FLAT INSIDE FACES POSITIONABLE IN FACE-TOFACE SPACED APPOSITION WITH SAID TWO OUTSIDE FACES OF SAID ADAPTER BLADE FOR FLAT FACE-TO-FACE CLAMPING CONTACT OF EACH FACE OF EACH OF THE TWO LEAVES OF THE ASSOCIATED FUSE CLIP. 